Bonjour,
I'm not from modeliosoft, but I think that this is not possible. At least with what the documented API. In fact the API is mostly useful for model manipulation trough the metamodel and provides also a few service but there is not so far some kind of "automation" giving access to top level features of modelio (those accessible from menus for instance). The doc is here
but if I'm not wrong you will not find anything releated to XMI.
Cheese,
Jean-marie